Throughout history it has been axiomatic to those of ordinary skill in the art that in order to perform delicate or meticulous processes and procedures with enhanced levels of control and with improved performance and outcomes the operators, technicians, surgeons, or other performers of the procedures must have good visual control of the various steps and details of the respective processes. Typically, the best way to improve visual control of a process is to increase the amount of visible light available in the workspace to brightly illuminate the target object or working area with shadow-free white light. One need only look at the high wattage lighting of a contemporary precision assembly line or at the bright lights of an operating room or dentist's office to appreciate how important good lighting is to the precise visual control and to the successful outcome of a delicate or precision procedure.
More recently, magnification and microscopy have been incorporated into meticulous testing and assembly processes and into similarly meticulous operating theater procedures to further improve the ability of the process operators to see what they are working on and to allow them to better visually control each step of the process. For example, ocular surgical procedures are now commonly performed under stereomicroscopes that enable the ocular surgeons to view the minute details and responses of various tissues within a patient's eye to the delicate steps of the procedures involved. In addition to the bright ambient room lighting of the operating room or surgical theater, stereomicroscopes can include their own internal sources of visible light to further illuminate the target tissues under the microscopic control of the operating surgeon.
Even more recently, electronic imaging has been incorporated into various processing and medical techniques to free the operators and surgeons from the awkward tedium of peering into the fixed eyepieces of conventional stereomicroscopes. Digital signal processing of such electronic images can provide an additional degree of visual acuity that can facilitate the performance of a meticulous process such as eye surgery. The present inventors recently provided a three dimensional high definition visual display platform that can take the images from a conventional stereomicroscope and present them to an operator or surgeon on a conveniently located screen. Moreover, the digital three dimensional images can be electronically processed to increase magnification or to improve signal quality and content.
However, there are circumstances where bright visible lighting can actually be detrimental to the performance of a meticulous process. For example, bright visible lighting can have negative effects which an operator such as a surgeon must endure. Hot operating room lighting can cause discomfort to a surgeon as well as to the patient. In some circumstances visors may need to be worn to reduce glare from the bright lights that must be in close proximity to the process target on an assembly line. Bright visible lighting also can take up room and floor space within an assembly line or operating theatre, further complicating the processes being performed. Reducing the lighting to improve operator comfort reduces the ability of the operators to see and visually control the processes.
Additionally, there are processes and procedures where bright visible lighting itself is detrimental to the outcome of the process. A photographic darkroom is an example of an environment where bright lighting, however useful to operator control, can be disastrous to the outcome of the process. Similar problems have been reported in ocular surgery such as cataract removal where bright lights of varying colors and wavelengths utilized in the surgeries have been found to be detrimental to the response of retinal tissue within the eye and may even have toxic effects on eye tissues.
Similarly, many types of modern eye surgery utilize lasers or other instruments to fuse or excise ocular tissues in order to correct medical conditions through processes such as fusing detached retinas to underlying tissues, sealing leaking retinal vasculature, removing opaque posterior capsule tissues from in front of the retina, or resculpting the shape and optical performance of a patient's cornea to correct distorted vision. To best accomplish these and other procedures the ocular surgeon would prefer to have the greatest possible visualization and resultant control of the meticulous process. However, bright ambient lighting or bright microscope lighting has exactly the opposite result because the patient's pupil constricts as a natural response to bright visible light and restricts or eliminates access to the target ocular tissues within the eye. Thus, prior to the present invention, an ocular surgeon had to sacrifice open pupillary access to internal eye tissues in exchange for illuminating those tissues with sufficient light to make them visible to operate on.
An acute example of a circumstance where bright visible lighting is actually a potential limitation to a successful result is the vision correction procedure known as laser-assisted in situ keratomileusis or “LASIK”. In LASIK a surgeon first measures the optical properties of a patient's eye to determine the amount and type of correction necessary to improve vision. This is best accomplished when the patient's pupil is completely dilated to its natural extent so that the greatest area of the patient's cornea can be measured for subsequent laser sculpting. Bright visible lighting interferes with this objective by causing the patient's pupil to constrict from its natural maximum dark or night vision diameter of approximately 8 millimeters to 1.5 millimeters or less, significantly limiting the area of the patient's cornea that can be measured and subsequently resculpted.
Though it is possible to dilate a patient's pupil with pharmaceutical compounds such as tropicamide, pharmaceutical dilation often results in an unnatural pupilliary diameter that can be distorted or off center. This further complicates the ocular measurement process by introducing another variable to the performing surgeon, potentially limiting control and impacting the outcome of the process. Additionally, tropicamide achieves dilation by temporarily paralyzing the muscles responsible for focusing in the patient's eye. This paralysis usually lasts at least a few hours and therefore the patient cannot safely operate a motorized vehicle to return home until the paralyzing effects of the chemical dilators have completely subsided or been chemically reversed by compounds such as dapiprazole.
Though it is possible to measure the optical functioning of a patient's eye in subdued light conditions in an effort to expand pupillary dilation without chemicals, it is not possible to perform the subsequent surgical sculpting procedure on the patient's cornea in the absence of visible light without sacrificing control. As a result, there is a significant need in the art for methods and apparatus that will enhance the outcome of such delicate or meticulous visually directed procedures.